一个平行四边形的底是18cm,高是10cm,它的面积是 ,和它等底等高的三角形的面积是 .
=15÷ =.
3÷ ==0.375= :24=24: .
=2.5:( )=125%=20÷( )=.
5: ==0.25= %
2.5÷ ==15: = %= (小数)